Non-electromechanical, pumpless liquid recirculation system for air-cooled condenser and cooler adiabatic pre-cooling system

ABSTRACT

A non-electromechanical, pumpless liquid recirculation system for adiabatic pre-cooling and evaporative heat exchange systems featuring an ejector device including motive fluid nozzle and an annular recirculating fluid chamber surrounding the nozzle. Motive make-up liquid under pressure is expelled from the nozzle into a mixing chamber. Recirculating fluid is introduced to and entrained with the motive make-up liquid at the outlet of the nozzle, and the motive force of the make-up liquid forces the combined make-up liquid and recirculating liquid out through the outlet of the ejector device to a water distribution system for the heat exchange system.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to adiabatic air pre-cooling systems for air-cooled condensers and coolers.

Description of the Background

Adiabatic air pre-cooling systems used with air-cooled condensers and air-cooled fluid coolers typically require an established liquid flow rate, typically of water, distributed over the entire adiabatic air pre-cooling media surface area, where a reservoir captures the residual liquid flow rate after leaving the adiabatic air pre-cooling media surface area, for subsequent disposal or recirculation. The purpose of the adiabatic air pre-cooling media is to pre-cool the air entering the air-cooled condensing coil or air-cooled fluid cooling coil thereby increasing thermal heat rejection capability. There are multiple adiabatic air pre-cooling medias, including but not limited to, corrugated cellulose paper pads, corrugated PVC pads, and wire type PVC pads. In one embodiment of an adiabatic system, water is distributed over the adiabatic media and the water that is not evaporated during the air pre-cooling process is disposed of down the drain. To eliminate water going to drain, recirculated system designs are employed. The current technology for recirculating liquid over the adiabatic air pre-cooling media is to utilize an electromechanical pump which requires electrical input power to provide the required liquid supply flow rate to establish the intended evaporation and heat transfer rates.

SUMMARY OF THE INVENTION

A limitation with utilizing an electromechanical pump is the requirement for both rotating and electrical components and rendering the equipment nonoperative in the event either one fails. Moreover, even partial operation of this electromechanical device may cause a significant reduction in the evaporation and heat transfer rates which in turn reduces the overall process efficiency. Current liquid pump technology leads to the eventual, random failure of either the mechanical or electrical components which typically occurs during the most critical process operating hours. Elimination of both mechanical and electrical components while maintaining desired liquid flow rate to the heat transfer component(s) would present a significant advantage. In addition, eliminating or reducing electrical costs (input power) as well as required maintenance are also beneficial. Finding a solution to eliminate rotating and electrical components as well as input power while providing the required liquid recirculation flow rate to the adiabatic air pre-cooling media has been particularly challenging.

This invention solves this problem by providing a solution that does not require any mechanical or electrical components to induce liquid flow, while providing both liquid recirculated and make-up flow rates to the adiabatic air pre-cooling media. Specifically, the inventors have discovered that driving a non-electromechanical, pumpless device (ejector) with an external, liquid make-up supply, coupled with the interconnecting piping, manual and modulating valves, electronic sensors, and liquid distribution system can successfully provide the necessary liquid flow rate onto the adiabatic air pre-cooling media for a wide range of operating conditions. This pumpless device coupled with an external, liquid make-up supply/pressure compliments one another to eliminate the requirement for an electromechanical device (i.e., pump).

According to a preferred embodiment of the invention, the recirculation system requires no motor or motorized pump. According to another preferred embodiment of the invention, the volume of entrained/recirculating fluid passing through the pumpless device in any time interval equals or exceeds the volume of the driving/motive fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the preferred invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show various embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is a representation of a prior art air cooled heat exchanger with adiabatic pads mounted on the upstream air side of the heat exchange coils over which pre-cooling water is circulated via electromechanical pump.

FIG. 2 is a schematic of a non-electromechanical, pumpless ejector device according to an embodiment of the invention.

FIG. 3 is a schematic of how a non-electromechanical, pumpless ejector device according to one embodiment of the invention may be used to replace an electromechanical pump in an otherwise standard adiabatic pre-cooled air cooled heat exchanger.

FIG. 4 is a schematic of how a non-electromechanical, pumpless ejector device according to an embodiment of the invention may be used to replace an electromechanical pump in an adiabatic pre-cooled air cooled heat exchanger without a controller or PLC.

Features in the attached drawings are numbered with the following reference numerals:

1 Ejector 3 Primary nozzle 5 Annular chamber 7 Side port 9 Recirculation tank 10 End Port 11 Mixing chamber 13 Adiabatic pads 15 Water distribution system 17 Water collection device 19 Bleed valve 21 Water Filter 23 Water pressure regulator 25 Modulating valve 27 Water pressure sensor 29 Water level sensor 30 Computer controller/plc 31 Inlet strainer 33 Recirulation tank strainer 40 Solonoid valve

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2-4 , the non-electromechanical pumpless ejector device of the invention 1 features primary nozzle 3. Primary nozzle 3 is surrounded by an annular chamber 5. Recirculating fluid is introduced to the annular chamber 5 via side port 7. Recirculating fluid reservoir or “recirculation tank” 9 may be located upstream of side port 7 for providing recirculating liquid flow to the side port 7 and annular chamber. Makeup fluid is introduced to the primary nozzle 3 via end port 10. A mixing chamber 11 is located downstream of the primary nozzle 3. A high velocity constant flowing makeup liquid steam is directed thru primary nozzle 3 which generates a low static pressure in mixing chamber 11 directly downstream from the nozzle 3. Recirculating liquid stream is discharged into the annular chamber via side port 7 and is entrained with the makeup fluid and forced into mixing chamber 11. Under the motive force of the supply of make-up liquid through the primary nozzle, the mixture of recirculating liquid and make-up liquid is supplied to the adiabatic cooling water return piping to the adiabatic cooling water distribution system.

FIGS. 3 and 4 are schematics showing how the ejector device 1 of the invention is used to replace the electromechanical pump of the prior art adiabatic pre-cooled air-cooled heat exchanger of FIG. 1 . Adiabatic pads 13 are wetted by water distribution system 15 which may be a distribution trough, spray nozzles, slotted or perforated tubes, and the like. Water that is not evaporated from the adiabatic pads is collected in a collection device 17 (e.g., tray, drain channel, tube, pipe, etc.) at the bottom of the pads. Where, according to the prior art, an electromechanical pump is provided to drive the collected water back to the water distribution system via adiabatic cooling water return piping, the present invention collects the not-evaporated water in a recirculation tank 9 from which it flows to side port 7 of the ejector 1. Flow of water from the recirculation tank 9 to side port 7 preferably requires no electromechanical pump and may be gravity or water pressure (by the height of the water in the recirculation tank) driven. The recirculation tank 9 may be provided with optional overflow feature and/or bleed valve 19. The motive force of the ejector of the invention is provided by the flow rate and pressure of the supply of make-up fluid. According to various embodiments, water filtration devices 21 and/or water softening and/or reverse osmosis devices (not shown) may be provided (not shown). A water pressure regulator 23 may be provided to regulate the pressure of the make-up water. A modulating valve, “MV1” 25 is preferably provided to allow for adjustment of the make-up liquid supply (motive) flow rate to the pumpless ejector device 1 of the invention, which in turn drives the desired total liquid flow rate to the adiabatic pre-cooling media. According to a preferred embodiment, the make-up fluid flow rate is equal to the evaporation rate of water from the adiabatic pads. Hence, the motive flow rate is adjusted using the modulating valve MV1 to match the adiabatic air pre-cooling media's evaporation rate. When the overall non-electromechanical, pumpless liquid recirculation system of the invention is in equilibrium with the evaporation rate from the adiabatic air pre-cooling media, the level of water in the recirculation tank remains constant. A controller computer or programmed logic circuit 30 may be provided according to one embodiment to monitor water pressure via electronic water pressure sensor 27 and the rate of evaporation at electronic water level sensor 29 and to adjust water pressure and flow rate vie water pressure regulator 23 and modulating valve 25, respectively. Controller/PLC may be hardwired to sensor and regulator/modulator devices or connected wirelessly.

According to an alternate embodiment, shown in FIG. 4 , a solenoid valve may be used in place of the computer controller/PLC, motorized valve MV1, pressure sensor and water level sensor of the embodiment of FIG. 3 . Inlet strainer 31 and recirculation tank strainer 33 may optionally be added as shown in FIG. 4 to any embodiment.

The total liquid flow rate at the outlet of the mixing chamber is the sum of the motive make-up supply liquid flow rate at a specific pressure, the recirculating liquid flow rate at side port 7 and the ejector's entrainment ratio. The entrainment ratio is primarily a function of nozzle geometry and annulus diameter and may be adjusted by adjusting liquid supply pressure and back pressure.

Overall, the non-electromechanical, pumpless liquid recirculation system will provide the total liquid flow rate to the adiabatic air pre-cooling media without any rotating or electrical components as well as comparable input power in comparison to an electromechanical pump.

It will be appreciated by those skilled in the art that changes could be made to the preferred embodiments described above without departing from the inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as outlined in the present disclosure and defined according to the broadest reasonable reading of the claims that follow, read in light of the present specification. 

1. A non-electromechanical liquid ejector comprising a make-up liquid chamber having an end port at a first end and a narrowed nozzle at a second end, an annular chamber located on an outside surface of said narrowed nozzle, said annular chamber in liquid communication with a source of recirculating fluid via a side port of said ejector, said annular chamber terminating at an outlet of said narrowed nozzle, and a mixing chamber located downstream of said outlet of said narrowed nozzle.
 2. An adiabatic pre-cooling system for an air-cooled condenser or cooler having no electromechanical pump, said adiabatic pre-cooling system comprising: a plurality of adiabatic pads mounted on said air-cooled condenser or cooler, a water distribution system mounted above said plurality of adiabatic pads, a water collection device mounted below said plurality of adiabatic pads, a recirculation tank located and configured to receive water from said water collection tray, a non-electromechanical liquid ejector comprising a make-up liquid chamber having an end port at a first end and a narrowed nozzle at a second end, an annular chamber located on an outside surface of said narrowed nozzle, said annular chamber in liquid communication with a source of recirculating fluid via a side port of said ejector, said annular chamber terminating at an outlet of said narrowed nozzle, and a mixing chamber located downstream of said outlet of said narrowed nozzle, a make-up water supply under pressure and configured to deliver make-up water under pressure to said end port of said non-electromechanical liquid ejector. 